Explain two-phase locking protocol, Operating System

Q. Show that a few schedules are possible under the two-phase locking protocol however not possible under the timestamp protocol and vice versa.

Answer: A schedule that is authorized in the two-phase locking protocol but not in the timestamp protocol is:

1660_Explain Two-phase locking protocol.png

This schedule isn't allowed in the timestamp protocol because at step 7 the W-timestamp of B is 1.

A schedule that is permitted in the timestamp protocol but not in the two-phase locking protocol is:

2316_Explain Two-phase locking protocol1.png

This schedule can't have lock instructions added to formulate it legal under two-phase locking protocol because T1 must unlock (A) between steps 2 and 3 and must lock (B) between steps 4 and 5.

Posted Date: 7/27/2013 3:54:00 AM | Location : United States






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